TM,
There have been long posts on this topic in General over the years (but I don't know whether or not they made the Archives)
I think you should stick with money (not stickers) for the following reason: Duckie is very smart and if she has already made the abstract connection between money and buying "things" then it is time to move on to bigger and better rewards which means SAVING.
(I lurk on this board because I find it interesting but really, what do you need with someone whose kids are 18 and 20???--but seriously, there are a few things I remember clearly, some I would do the same way and some I would not--this is one I would do the same way--so occasionally I post something I hope is useful to someone.)
The goals of all this work and allowance stuff is to create financially responsible young adults and in my opinion--it's never too early to start. If you give kids money for each chore completed or money in a grocery store, you are creating an "instant gratifier" in my opinion. The the kid spends the quarters on "junk" and you end up buying the Barbies anyway
Back to Duckie:
Here is what I would do because it directly links money to the items desired. First determine what she wants (one "big" item) and then determine the cost. Make a chart with a picture of the item and a picture of the money needed (I did this when I could just write 12 dollars) but you could photocopy a dollar, reduce it and put 12 on a chart or just write the number 12 and put one picture and put an envelope underneath. For very concrete kids, a baggie is good because they can see the $$.
THEN--and this is the saving part, teach her that 4 quarters = one dollar. So if you want to give her a quarter because she did something extra or whatever, fine. Put the quarters in a glass jar next to the chart (with a slit in the lid.) Allow the child to take out quarters to buy small stuff but every time there are 4 or more quarters, ask her if she would like a dollar for her savings for X. This is the only way I have found to get kids to realize that today's small expenditures cut into future large purchases.
I have to say that both my kids are good money managers and although they may buy more "little stuff"--mostly unnecessary food in restaurants with friends than I want, they are fully aware that those types of expeditures undermine long-term savings goals. In addition to whatever they think they "need" they are required to contribute to college tuition so they have a lot of potential conflict between easy short term gratification and long term savings. Ex-difficult child recently figured out that his tuition contributions are going to make a car unrealistic for four years--o well--a car is unrealistic in NYC anyway but I was glad he could figure out that it was monetarily unrealistic rather than my just telling him, "no one has a car in NYC."
So I beleive that coverting to a currency system as early as possible and teaching equivalent money values is very important.
Another imprtant concept is saying, "NO" when the child begs in stores. I used to ask my kids before they went to the store with me (a situation I tried to avoid, I admit) if they wanted to take any of "their" money from the jar. Ex-difficult child caught on sooo quickly that if he took two quarters to the store, he was delaying getting whatever was on the chart.
Finally, when kids get older, they want/need things that would take them too long to earn unless you want to pay them a very high amount of money for chores or have them wait 5 years. Enter the negotiation phase of splitting by matching funds: I will contribute 2 dollars to every one they save toward a whatever, a CD player, incredibly expensive gym shoes, etc. Obviously, I could contribute 3 dollars and so on--depended on how much I thought the item was a real need vs a passing fancy.
In addition to chores, I think that kids should have money just for existing if the family can afford it. It then becomes the child's decision whether to put this money in the jar (spending) or in the envelop on the chart--saving. I tried to encourage them to save some of their allowance but didn't insist--it was their money. The "free" allowance was set at a dollar per year of age per week but I may be hopelessly out of date (since I stopped paying easy child an allowance 8 years ago at age 12) because I discontinued the 'free' allowance AS SOON AS they could earn money on their own. Then they switched from envelopes to bank accounts (actually they still used the envelopes and then put the money in the bank at intervals.) This part of the system only works if the child can earn more than the free allowance. For both my kids, this happened, probably because I didn't ever give them allowances as big as their friends so they had motivation to work.
If you keep the long-term goal in mind, I think you will see why some sort of "spending account" and a "savings account" is very helpful.
Martie